The invention relates to telephones and, more particularly, to the detection of an off-hook telephone and the receiving of an incoming telephone call through the disconnected telephone.
Occasionally, a telephone may become disconnected from an incoming telephone line, often referred to as being "off-hook ", preventing any incoming telephone calls from being received and any outgoing telephone calls from being transmitted. For example, a receiver of the telephone may be accidently left off of the hook, the receiver may be knocked off of the hook by a small child, or depending on the type of telephone, the On/Off button of the receiver may have been accidentally pressed.
Currently, many telephone companies provide the service of transmitting a tone through the telephone line to be heard through the receiver of an off-hook telephone after a certain period of time of disconnection, to notify a person that their telephone is disconnected. Some telephone companies convey a first tone, a second louder tone, and a recorded message which may be heard through the receiver. However, the tones and message are transmitted for a only certain length of time, after which the receiver is silent and the telephone is disconnected from the telephone line. If a person is not near the receiver and does not hear the tones or message, the person will not be notified to hang up the telephone or re-connect the telephone to the incoming telephone line.
An off-hook detection circuit for detecting when a telephone has been taken off the hook is disclosed in U.S. Pat. No. 5,317,626 issued May 31, 1994 to Jaynes et al. and emitled "Wake-Up and Reminder System for a Telephone ". The system includes a first relay for disconnecting the telephone from the telephone line, an off-hook detection means, and a second relay for disconnecting the telephone from a ringing device and connecting the telephone to a recorder which plays a pre-recorded message. However, when the off-hook detection circuit detects that the telephone has been taken off the hook, the second relay disconnects the telephone from the ring line and incoming calls cannot be received.
Therefore, what is needed is an apparatus and method for receiving incoming calls even if the telephone has been disconnected from the telephone line.